Hurricane EARL (Text)

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HURRICANE EARL DISCUSSION NUMBER 25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072010
1100 AM AST TUE AUG 31 2010
THE EYE HAS BECOME OBSCURED ON VISIBLE IMAGES AND THIS IS REFLECTED
IN A DECREASE IN THE DVORAK NUMBERS AND IN AN INCREASE IN THE
PRESSURE TO 939 MB. THIS APPARENT WEAKENING IS MOST LIKELY RELATED
TO AN ONGOING EYEWALL REPLACEMENT CYCLE AS INDICATED BY THE DOUBLE
EYE STRUCTURE OBSERVED ON MICROWAVE DATA AT 1035 UTC. HOWEVER...AN
AVERAGE OF THE FLIGHT-LEVEL WINDS AND SFMR DATA FROM THE AIR FORCE
RECONNAISSANCE PLANE STILL SUPPORTS AN INITIAL INTENSITY OF 115
KNOTS. NO CHANGE IN INTENSITY IS EXPECTED TODAY BUT THERE IS A
CHANCE FOR EARL TO STRENGTHEN A LITTLE DURING THE NEXT 24 HOURS IF
THE OUTER EYEWALL SHRINKS. DESPITE THE FLUCTUATIONS IN INTENSITY...
EARL MOST LIKELY WILL RETAIN CATEGORY FOUR STATUS FOR THE NEXT 48
HOURS. A GRADUAL WEAKENING SHOULD BEGIN THEREAFTER AS THE SHEAR
INCREASES.
EARL HAS CONTINUED TO WOBBLE DURING THE PAST FEW HOURS BUT THE
AVERAGE MOTION IS TOWARD THE WEST-NORTHWEST OR 300 DEGREES AT 12
KNOTS. EARL HAS BEEN STEERED BY THE FLOW AROUND A SUBTROPICAL RIDGE
EXTENDING FROM THE EASTERN UNITED STATES EASTWARD ACROSS THE
ATLANTIC. THIS PATTERN WILL KEEP EARL ON A GENERAL WEST-NORTHWEST
TO NORTHWEST TRACK DURING THE NEXT 24 TO 48 HOURS. THEREAFTER...THE
SUBTROPICAL RIDGE WILL MOVE EAST AND EARL WILL LIKELY TURN NORTH AND
NORTHEAST BETWEEN THE RIDGE AND MID-LEVEL TROUGH OVER THE EASTERN
UNITED STATES. THIS IS THE SCENARIO PROVIDED BY MOST OF THE
DYNAMICAL MODELS. THE OFFICIAL FORECAST HAS SHIFTED A LITTLE TO THE
WEST BEFORE 48 HOURS AND IS ON THE WESTERN EDGE OF THE GUIDANCE
ENVELOPE.
GIVEN THE TRACK AND THE LARGE AREA OF TROPICAL STORM FORCE WINDS...A
HURRICANE WATCH WILL LIKELY BE REQUIRED FOR A PORTION OF THE
MID-ATLANTIC COAST LATER TODAY. INTERESTS FROM THE CAROLINAS
NORTHWARD TO NEW ENGLAND SHOULD MONITOR THE PROGRESS OF EARL.
THERE IS STILL CONSIDERABLE UNCERTAINTY AS TO HOW CLOSE THE
HURRICANE WILL COME TO THE U.S. EAST COAST.
FORECAST POSITIONS AND MAX WINDS
INITIAL 31/1500Z 21.2N 67.9W 115 KT
12HR VT 01/0000Z 22.3N 69.7W 115 KT
24HR VT 01/1200Z 24.8N 71.7W 120 KT
36HR VT 02/0000Z 27.3N 73.5W 115 KT
48HR VT 02/1200Z 30.5N 75.0W 115 KT
72HR VT 03/1200Z 36.5N 73.0W 100 KT
96HR VT 04/1200Z 43.5N 66.0W 80 KT
120HR VT 05/1200Z 52.5N 57.0W 55 KT...POST-TROP/EXTRATROP
$$
FORECASTER AVILA
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